I got a friend who really damaged his back a few years back when he fell on his head and damged his back. He can stand, walk, run hes not disablled just after a period of time he gets pain. I told him i'd ask him do you think deadlifts would be a bad thing or a good thing?
I'm talking 45 lbs, or maybe even less.
"It is the soldier, not the reporter who has given us the freedom of the press.
"It is the soldier, not the poet, who has given us the freedom of speech.
"It is the soldier, not the campus organizer, who gives us the freedom to demonstrate.
"It is the soldier who salutes the flag, who serves beneath the flag, and whose coffin is draped by the flag, who allows the protester to burn the flag."
are you also his physician? if not, then i don't think neither you nor us have the capability to assess his readiness for weight training.
Is the pain coming from the spine or the muscles?
but if i guess if it worths the risk, you can start out with something like goodmorning with a broom stick to see how it goes, then gradually add 5 of 10 lbs.